1. Technical Field
The present invention relates to a white toner used for electrophotographic image forming process, more particularly to a white toner capable of forming both of a high gloss image and a low gloss image, and to an image forming method and an image apparatus using the white toner.
2. Description of the Related Art
Full-color images using four colors of yellow, magenta, cyan, and black have been widely used in recent years although electrophotographic images are generally printed in black. In such a case, an image is formed on a white substrate such as paper by using these four color toners. However, good coloring image are not obtained on a colored substrate such as black paper or colored paper or a transparent substrate such as a transparent film by using only four color toners. For this reason, Japanese published unexamined application No. JP-2006-220694-A discloses a method of using white toner as the fifth color toner to make a white background image.
White toner is used to make a white background on a black or colored substrate such as paper, or used for a white background of a transparent substrate such as film. In this case, the white toner is required to have masking characteristics. The masking characteristics mean the ability to hide what exists below the background on which the white toner is fixed. In the case of white color, only a fixed white toner is used for white coloring and it is therefore necessary to scatter and reflect all incident light. If there is a little transmissive light, the obtained image is not vivid or clear. To solve this problem, for example, Japanese published unexamined applications Nos. JP-H01-105962-A and JP-2000-056514-A disclose improving masking characteristics.
On the other hand, in the white image market, it is known that preferred gloss is different according to applications as white offset ink includes high gloss grade and low gloss grade. In the printing field, inks are exchanged to obtain desired glossiness. However, the electrophotography can comply with only a limited application, since it is difficult to exchange a toner for each application because processes from providing a toner to forming images are complicated.